Laparoscopy dates back to the turn of the 20th Century. Early laparoscopic techniques were used primarily for diagnostic purposes to view the internal organs, without the necessity of conventional surgery. Since the 1930s, laparoscopy has been used for sterilization and, more recently, for suturing hernias. U.S. Pat. Nos. 4,919,152 and 4,944,443 are concerned with techniques for suturing hernias. Another recent innovation is the use of laparoscopic surgery for removing the gallbladder.
In the course of performing laparoscopic procedures in the abdomen, it is necessary to raise the abdominal wall to create space in which to work. A well-known method of raising the abdominal wall is to insufflate the abdominal cavity with a suitable insufflation gas, such as air, or carbon dioxide. A significant disadvantage of gas insufflation is that instruments must be passed into the abdominal cavity through gas-tight seals, which significantly reduce the surgeon's feel of the instruments.
Several mechanical alternatives to gas insufflation have been proposed. The Gazayerli Endoscopic Retractor Model 1, described in SURGICAL LAPAROSCOPY AND ENDOSCOPY, Vol. 1, No. 2, 1991, pages 98-100, has a rigid rod with a hinged blade at the distal end. The blade can rotate through 360 degrees about an axis perpendicular to the long axis of the rod. The blade is aligned with the long axis of the rod for insertion into the abdomen through a small puncture. Once inside the abdomen, the blade is swivelled through about 90 degrees to form a T-shaped structure. The proximal end of the rod can be raised by hand or by a rope, pulley and weight arrangement. Raising the rod causes the blade to engage the abdominal wall and to lift it.
French patent application no. 90-03980 shows a wire structure that is threaded into the belly through a small puncture to engage and to lift the abdominal wall. The application also shows a fan retractor that has a first angle-shaped member having a first leg that engages with the abdominal wall, a tubular second leg having a bore, and a third leg, remote from the first leg, that has a hook-shaped member on its end distal from the second leg. A second angle-shaped member has a first leg that engages with the abdominal wall, a second leg that pivots within the bore of the second leg of the first angle-shaped member, and a third leg, remote from the first leg, that serves as an operating lever for the second angle-shaped member. The first legs of the angle-shaped members are closed together to insert them into the abdominal cavity through an incision. The third leg of the second angle-shaped member is then operated to spread the first leg of the second angle-shaped member apart from the first leg of the first angle-shaped member. The first legs are engaged with the peritoneum inside the abdominal cavity. A lifting force is then applied to the hookshaped member to lift the retractor and hence to lift the abdominal wall.
U.S. patent application Ser. No. 706,781, the application of which this application is a Continuation-in-Part, describes a number of different mechanical devices that are inserted through one or more punctures into the belly. All or part of the device is then lifted to lift the abdominal wall away from the underlying abdominal organs. One of the devices described in the prior application is a fan retractor that is inserted in a closed condition into the abdominal cavity, spread apart once inside the abdominal cavity, and brought into contact with the peritoneum inside the abdominal cavity. The apparatus is then lifted to lift the abdominal wall.
The known fan retractors are all intended for intra-abdominal placement. It is difficult to place the peritoneum-engaging elements of such devices inside the abdominal cavity adjacent to the peritoneum without snagging the bowel or omentum. It is often necessary to make multiple attempts at inserting the retractor before the fan retractor can be correctly positioned with its peritoneum-engaging elements adjacent to the peritoneum with no bowel or omentum caught between the peritoneum-engaging elements and the peritoneum. Insufflating the abdomen before inserting the fan retractor does not eliminate the risk of snagging.
If the retractor is inserted, lifted, and maintained in a lifted state with an unrecognized loop of bowel caught between the peritoneum-engaging elements of the retractor and the peritoneum, trauma or necrosis to that loop of bowel may occur, with significant morbidity or mortality.
Known fan retractors have a substantially constant stiffness along the length of their peritoneum-engaging elements. This causes the pressure that the peritoneum-engaging elements exert against the peritoneum to increase sharply towards the ends of the peritoneum-engaging elements. High pressure can cause trauma to the peritoneum, and there is a risk that the ends of the peritoneumengaging elements will penetrate the peritoneum.
The peritoneum-engaging elements of known fan retractors move independently of one another. This can lead to the peritoneum-engaging elements of the fan retractor being asymmetrically placed within the abdominal cavity, which results in the peritoneum-engaging elements providing the retracting force unequally. With asymmetrical placement, there is the risk that the more heavily loaded peritoneum engaging element will traumatize or penetrate the peritoneum.
The lifting force applied by known fan retractors is generally determined by the lifting result obtained. If, for some reason, the abdominal wall fails to lift, the lifting force could accidentally be increased to the point at which trauma to or penetration of the peritoneum occurs.
Known fan retractors are rigidly attached to lifting bars such that, if the lifting bar is carelessly lowered at the end of treatment, the lifting bar can push the fan retractor into the abdomen, and cause a compression injury to the underlying organs.